Insomnia symptoms occur in up to 30-50% of obstructive sleep apnea (OSA) patients. The prevalent co- occurrence of insomnia with OSA may not only serve to increase illness burden, it may also represent a substantial impediment to OSA treatment adherence. Insomnia in OSA has generally been viewed as a consequence of OSA (and is so specified in the existing clinical care guidelines). In patients with 'Primary Insomnia', sleep initiation and sleep maintenance problems occur with equal prevalence. In contrast, in patients with OSA, preliminary data gathered by the study investigators suggest that sleep maintenance insomnia is more pronounced and that CPAP treatment may ameliorate sleep maintenance but not sleep initiation insomnia. This gives rise to the primary hypothesis that insomnia in OSA patients is a heterogenous disorder which in some cases may be directly due to the OSA, while in others it is independent of the OSA. Accordingly, the investigators propose a controlled clinical intervention trial using a continuous positive airway pressure+contact control (CPAP+CC) arm, a sham-CPAP+CC arm and a CPAP+cognitive behavioral therapy for insomnia (CPAP+CBT) arm to assess the extent to which OSA treatment affects insomnia, whether these effects are limited to sleep maintenance insomnia (which is likely to be due to OSA) as opposed to sleep initiation insomnia (which may generally be independent of OSA), and whether CBT provides additional benefit. Inclusion of a sham-CPAP component is an innovative and essential component in testing this hypothesis because of the significant placebo effects that can occur in open-label insomnia research. Consistent with the goals of the Program Announcement, the proposed study design is a pilot clinical trial of 108 subjects, 54 with sleep initiation symptoms and 54 wih sleep maintenance symptoms, who will be randomized to CPAP+CC, sham- CPAP+CC, or CPAP+CBT (double-blind), thus creating six groups (18 subjects per group). The study aims include assessing CPAP, sham-CPAP, and CPAP+CBT effects on insomnia severity, daytime outcomes (both subjective and objective) and objectively measured CPAP adherence. The proposed pilot study is a crucial first step in the long-term objective of effectively treating insomnia symptoms in OSA and would accomplish several key goals as outlined in the program announcement: 1) Determine the feasibility of CPAP, sham-CPAP, and CPAP+CBT in OSA patients with insomnia; 2) Assess adherence to the study intervention and 3) Identify study parameters and covariates for sample size estimates for a future definitive multi-site study; particular emphasis will be placed on the role of covariates such as age, gender and race. The proposal has significant public health ramifications in that it represents a novel perspective on insomnia in OSA that challenges existing clinical paradigms, will identify characteristics of insomnia independent from OSA versus insomnia due to OSA, and could ultimately improve patient adherence to CPAP therapy by identifying patients who warrant targeted insomnia therapy that will supplement their CPAP therapy. PUBLIC HEALTH RELEVANCE: Nearly half of all patients with obstructive sleep apnea have insomnia symptoms, and in some, but not all cases, these insomnia symptoms are caused by the obstructive sleep apnea. The purpose of this study is to find out what type of insomnia symptoms are caused by obstructive sleep apnea and therefore most likely to respond to obstructive sleep apnea treatment with continuous positive airway pressure (also known as CPAP) and if additional treatment with cognitive-behavioral therapy for insomnia is beneficial. (End of Abstract)